Optical Characteristics of a Magnetocentrifugal Disk Wind in the Visual, Ultraviolet, and X-ray Spectral Ranges

Abstract

The optical characteristics of a magnetocentrifugal disk wind from T Tauri stars that we calculated based on the MHD models of Safier (1993a, 1993b) are presented. For an outflow rate in the range \(10^{-10}{-}10^{-7} M_{\odot}\) yr\({}^{-1}\) we calculated the critical angles at which the wind becomes opaque in the optical, ultraviolet, and X-ray parts of the spectrum. The illumination of the outer regions of protoplanetary disks involved in creating a photoevaporating wind by the star and the conditions for observing young stars in different wavelength ranges depend on these angles. We show that at the early evolutionary stages of T Tauri stars the disk wind is capable of completely shielding the star and preventing the direct illumination of the peripheral disk regions in both optical and X-ray ranges. By absorbing the bulk of the stellar radiation, the disk wind itself becomes a radiation source capable of heating the disk. We show that at an outflow rate \({\geq}10^{-9} M_{\odot}\) yr\({}^{-1}\) the fraction of the radiation absorbed by the wind can reach \(60\%\). Hot accretion spots can contribute significantly to the absorbed radiation. This allows the disk wind to be considered as an important infrared radiation source of T Tauri stars.